The invention applies, without being restricted thereto, to the measurement of tyre pressure, in particular for construction machinery tyres.
The prior art, notably U.S. Pat. No. 6,931,934, discloses a pressure-measurement member arranged inside the space delimited by the tyre and the rim. The member is of a passive type and comprises a protective housing. The member also comprises a test body and the housing comprises a wall supporting a pressure-measurement surface functionally connected to the test body. Specifically, this wall comprises an indentation designed so that the wall is positioned in contact with the test body. Under the effect of the external pressure applied to the wall, the indentation mechanically transmits the pressure to the test body which is therefore able to detect the pressure external to the member.
However, repeated mechanical loadings applied by the indentation to the test body upon contact therewith lead firstly to wear on the test body, thus impairing the pressure measurement, and secondly to detachment of the test body from its support, thus rendering the member unusable.
Further, because the member is of a passive type, each measurement member has to be calibrated once it has been manufactured, and this is therefore a painstaking and costly exercise. It also requires calibration data to be memorized in a processing unit belonging to the member. That increases the complexity and cost of the system. Further, the calibration data are a source of measurement errors.
It should also be noted that, when the member is not completely sealed throughout its entire life, it is not protected from chemical attack, notably from attack by the products used for maintaining the rims and the tyre. This prolonged exposure to chemical attack impairs the test body and therefore the pressure measurement.